The present invention relates to a can opener, more particularly, but not exclusively, to a manually operable can opener of the kind having two handles pivoted together.
Several well known can openers comprise a pair of handles pivoted together, wherein one handle carries a slideably mounted or a fixed cutting wheel or a knife and the other handle carries a toothed or driving wheel, which is mounted on to a shaft which in turn is rotated by a butterfly plate or handle.
It has long been recognized that there is a need for a simple can opener, operable with one hand, and of simple construction. Application Number GB 2161449A discloses a can opener wherein the cutting element is slideably mounted so that a pair of handles may be squeezed together to cause the cutter to penetrate the can, and a further handle causes the shaft holding the drive wheel to rotate.
In this and other cited references the cutter clement is mounted in such a way that it can be moved on its mounting either slideably or by rotation on an eccentric or other means, in order to nip or penetrate the can top or wall. Other cited references also disclose a drive wheel which is mounted onto a drive shaft and then rotated by a ratchet or clutch device.
All of the above disclosures have disadvantages of cost, gearing or complexity of manufacture and use.
According to one aspect of the present invention, there is provided a can opener comprising first and second handle members pivotally connected about an axis to be moveable between an open disposition and a closed disposition, a cutting wheel or knife means being rigidly mounted onto the first handle member, a radially facing slot formed through a part of said first handle member. and a drive wheel partly protruding through said slot to engage the rim of the can and press it against the cutting wheel or knife means.
The drive wheel may be mounted rotatably onto a support shaft or rivet which is held slideably in a slot in the main plate of the first handle.
The support shaft is preferably not fixed to the drive wheel and does not supply any rotative drive to the wheel.
Preferably, said shaft does not rotate, but slides in said slot and has a suitable larger diameter head on the same side as the cutting device of said handle plate.
The first handle member is shaped as a doubly bent plate and said slot is provided in the portion thereof connecting the two bends.
The large drive wheel is thus free to rotate while lying flat on the side of the first handle plate, beyond the double bend and rotatable around the shaft, which is free to slide in the slot provided in that plate.
The second handle member may have a suitable hole and bearing material in the upper portion of the handle near to the drive wheel and which fits over the same shaft or rivet on which it freely rotates.
This second handle member may also be fitted with a ratchet device or clutch so that, when the two handles are squeezed together, the ratchet causes the drive wheel to rotate in that direction only.
A return spring may be fitted, conveniently underneath the second handle member and above the drive wheel, to cause the second handle to move apart from the first handle after the squeeze movement.
An appropriate end of this spring, where it is mounted on to the second handle, may also be used to operate said ratchet and thus avoid the use of a separate spring part for this purpose.
This spring may conveniently be of a coil spring form and may be so mounted that one end is fixed to the first handle member, and the other to the second handle member.
The spring can thus also cause the second handle member, when released from the nip or cutting position, to return to the non-nip or release position by causing the shaft to slide down its slot and, in so doing, to withdraw the drive wheel teeth from the side of the first handle member near to the cutting wheel or knife means, thereby releasing the can without further and possibly unnecessary opening of the handles.
The first handle plate may also have a sloped or conveniently shaped approach to the said slot in the double bend on the same side of said handle as the cutter, to facilitate the insertion of the unopened can into the space below the cutter and which slope can ensure the correct angle of the can to the cutter. The drive wheel teeth are at this stage below the surface of this plate to facilitate correct insertion of the can.
When the second handle is first squeezed towards the first handle after the can is in place, it presses against a cam or suitable shaped portion of the first handle plate, which provides strong leverage to lift the shaft or rivet, holding the drive wheel along its slot, so that the drive wheel teeth rise through the slot in the double plate bend and engage the rim of the can on its underside, forcing it against the fixed cutter device to penetrate the top of the can.
It will be observed that the drive wheel is already rotating due to the ratchet drive on the second handle and this rotation causes the drive wheel to move further along its slot in a direction roughly parallel to that of the axis of the first handle, due to the engagement of the hardened teeth of said wheel with the softer material of the rim of the can.
This movement causes the second handle member, the drive wheel, the spring and the ratchet system all to move in the above direction by a few millimeters, thus the tip of said second handle member becomes disengaged from the cam on the first handle and enables the full squeeze movement of the second handle member to be completed.
On releasing the spring loaded second handle at the completion of the squeeze action, it will open outwardly until the upper portion of the second handle member above its fulcrum at the shaft or rivet encounters a further cam or similar fixed object on the side of the first handle member remote from the cutter, which limits the normal opening of the handles one from the other for the next squeeze.
However, if the second handle member is pushed against the above described spring beyond this point, the drive wheel and the second handle and spring will move along the said slot in the opposite direction to that which caused the nip and cutting, and the spring will move the drive wheel away from the rim of the can and back towards the other cam, and thereby form the leverage for the nip penetration of the can.
The can may be firmly held while the two handle members are held together to facilitate the pouring of hot soup or the like from the can, which can then be discarded by opening the handles as described above.
A magnet may also be fitted at or near to the cutter to retrieve the severed lid of the can.
The use of a large drive wheel eliminates the need for gearing and the like which was tried in Application Number EP 0503931 B1 in order to reduce the number of squeezes required to open a can. A large wheel can not reasonably bc used as in this example, to open a small or irregularly shaped can, or where it is desired to cut off the top of the can by cutting the cylindrical can wall. For this reason, the present invention is conveniently, but not exclusively, arranged to cut the lid or inner top surface of the can, thus leaving a safe upper edge and avoiding spillage, while the large wheel rotates around the outside lower edge of the can rim and causes a small cutter to go around the upper inside edge of the can and remove the top surface, leaving a smooth edge of the can.
It will be clear this invention is simple and has a minimal number of parts and is assemblable with only one rivet or shaft.